Nickel-aluminum blocker film multiple cavity controlled transmission coating

ABSTRACT

The invention provides a glazing sheet and a coating on the glazing sheet. The coating comprises, in sequence moving outwardly from the glazing sheet, a dielectric base coat comprising oxide film, nitride film, or oxynitride film, a first infrared-reflective layer, a first nickel-aluminum blocker layer in contact with the first infrared-reflective layer, a first dielectric spacer coat comprising an oxide film in contact with the first nickel-aluminum blocker layer, a second infrared-reflective layer, a second nickel-aluminum blocker layer in contact with the second infrared-reflective layer, a second dielectric spacer coat comprising an oxide film in contact with the second nickel-aluminum blocker layer, a third infrared-reflective layer, a third nickel-aluminum blocker layer in contact with the third infrared-reflective layer, and a dielectric top coat comprising an oxide film in contact with the third nickel-aluminum blocker layer. Also provided are methods of depositing such a coating.

RELATED APPLICATIONS

This is a divisional of U.S. application Ser. No. 14/663,644, filed Mar.20, 2015, the teachings of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to thin film coatings for glass and othersubstrates. In particular, this invention relates to controlledtransmission coatings that are used on insulating glass units, laminatedglass assemblies, and other glazing assemblies. Also provided aremethods and equipment for producing such coatings and glazingassemblies.

BACKGROUND OF THE INVENTION

Glass sheets and other substrates can be coated with a stack oftransparent, metal-containing films to vary the properties of the coatedsubstrates. Particularly desirable are coatings characterized by theirability to transmit visible light while reducing the transmittance ofother wavelengths of radiation, especially radiation in the infraredspectrum. These characteristics are useful for minimizing radiative heattransfer while controlling visible transmission. Coated glass of thisnature is useful as architectural glass and as automotive glass.

Low-emissivity coatings and other controlled transmission coatingstypically include one or more infrared-reflective films and two or moreantireflective transparent dielectric films. The infrared-reflectivefilms reduce the transmission of radiant heat through the coating. Theinfrared-reflective films commonly are conductive metals (e.g., silver,gold, or copper), although transparent conductive oxides (e.g., ITO) orconductive nitrides (e.g., TiN) may also be used. The transparentdielectric films are used primarily to reduce visible reflection, toprovide mechanical and chemical protection for the sensitiveinfrared-reflective films, and to control other optical coatingproperties, such as color. Commonly used transparent dielectrics includeoxides of zinc, tin, and titanium, as well as nitrides and oxynitridesof silicon. Such coatings can be deposited on glass sheets through theuse of well-known magnetron sputtering techniques.

It is known to deposit a thin metallic layer directly over aninfrared-reflective silver film to protect the silver film duringdeposition of a subsequent dielectric layer and/or during tempering orany other heat treatment. These protective layers (sometimes called“sacrificial layers” or “blocker layers”) have been formed of variousmaterials, such as titanium, niobium, niobium-titanium, or NiCr.

The particular material from which the blocker layer is formed impactsvarious properties and characteristics of the coating. Titanium blockerlayers, for example, have been found to impart excellent scratchresistance in low-emissivity coatings. They also adhere well to both anunderlying silver film and an overlying oxide film. Niobium has beenfound to be an advantageous blocker layer material as well. In addition,niobium-titanium has been found to be particularly beneficial in certainrespects.

It is sometimes necessary to heat coated glass sheets to temperatures ator near the softening point of glass (726 degrees C.), e.g., to temperthe glass or enable it to be bent into desired shapes. Tempering isimportant for glass used in automobile windows, and particularly forglass used in automobile windshields, as well as in variousarchitectural glazing applications. Upon breaking, tempered glassexhibits a break pattern in which the glass shatters into many smallpieces, rather than into large dangerous shards. During tempering,coated glass is typically subjected to elevated temperatures on theorder of about 700 degrees C. Moreover, the coated glass must be able towithstand such temperatures for substantial periods of time. Certainfilm stacks having silver as the infrared-reflective film are not ableto withstand such high temperature processing without unacceptabledeterioration of the silver film.

To avoid this problem, glass sheets can be heated (e.g., bent ortempered) before they are coated. The desired films can then be appliedafter heating. This procedure, however, tends to be complicated andcostly and, more problematically, may produce non-uniform coatings.

In many cases, it is desirable for temperable low-emissivity coatings tohave only an upper blocker layer (i.e., without any lower blockerlayer). In other cases, a reflective silver film is protected fromdeterioration at high temperatures by sandwiching the silver between twometallic blocker layers. In such cases, the two blocker layers are thickenough and reactive enough that when the coated glass is heated to hightemperatures, these films capture oxygen and/or nitrogen that wouldotherwise reach and react with the silver.

In addition to the infrared reflection provided by low-emissivitycoatings, these coatings can provide desired shading properties. As iswell known, the solar heat gain coefficient (SHGC) of a window is thefraction of incident solar radiation that is admitted through a window.There are a number of applications where low solar heat gain windows areof particular benefit. In warm climates, it is especially desirable tohave low solar heat gain windows. For example, solar heat gaincoefficients of about 0.4 and below are generally recommended forbuildings in the southern United States. Further, windows that areexposed to a lot of undesirable sun benefit from having a low solar heatgain coefficient. For example, windows on the east or west side of abuilding tend to get a lot of sun in the morning and afternoon. Forapplications like these, the solar heat gain coefficient of a window canplay a vital role in maintaining a comfortable environment within thebuilding. Thus, it is beneficial to provide windows of this nature withcoatings that establish a low solar heat gain coefficient (i.e., highshading ability coatings).

Tradeoffs are sometimes made in low-emissivity coatings in order toobtain the desired shading properties. For example, the films selectedto achieve a low SHGC may have the effect of restricting the visiblereflectance to a higher level than is ideal. As a consequence, windowsbearing these coatings may have a somewhat mirror-like appearance. Itwould be desirable to provide a high shading ability coating that hassufficiently low visible reflectance to obviate this mirror-likeappearance problem.

In addition to having undesirably high visible reflectance, thereflected or transmitted colors of conventional high shading abilitycoatings may be less than ideal. For example, these coatings may exhibithues that are more red or yellow than is desired. To the extent acoating has a colored appearance, it is pleasing if the coating exhibitsa transmitted and reflected hue that is blue or blue-green. The chromaof these coatings may also be greater than is desired. In most cases, itis preferable to provide a coating that is as color neutral (i.e.,colorless) as possible. Thus, the reflected or transmitted colors ofconventional low solar heat gain coatings may be less than ideal, bothin terms of hue and chroma.

Some high shading ability low-emissivity coatings that provideadvantageous properties have been commercially available for years.While some of these coatings have been more than acceptable, it would bedesirable that they have even better mechanical durability, chemicaldurability, or both.

It would be desirable to provide controlled transmission coatings basedon a blocker layer material that can provide exceptional mechanicaldurability. It would be particularly desirable to provide such acontrolled transmission coating based on a blocker layer material thatalso provides exceptional moisture resistance. Further, it would bedesirable to provide controlled transmission coatings that also exhibitpleasing color in reflection, transmission, or both.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional, broken-away view of a substratehaving a surface coated with a multiple cavity controlled transmissioncoating in accordance with certain embodiments of the present invention.

FIG. 2 is a schematic cross-sectional, broken-away view of a substratehaving a surface coated with a multiple cavity controlled transmissioncoating in accordance with other embodiments of the invention.

FIG. 3 is a schematic cross-sectional, broken-away view of amultiple-pane insulating glazing unit that includes a pane having asurface coated with a multiple cavity controlled transmission coating inaccordance with certain embodiments of the invention.

FIG. 4 is a schematic cross-sectional, broken-away view of amultiple-pane insulating glazing unit that includes a pane having aninner surface coated with a multiple cavity controlled transmissioncoating and an outer surface coated with a hydrophilic coating inaccordance with certain embodiments of the invention.

FIG. 5 is a schematic cross-sectional, broken-away view of amultiple-pane insulating glazing unit that includes a first pane havingan inner surface coated with a multiple cavity controlled transmissioncoating and a second pane having an outer surface coated with atransparent conductive coating in accordance with certain embodiments ofthe invention.

FIG. 6 is a schematic cross-sectional, broken-away view of amultiple-pane insulating glazing unit that includes a first pane havingan inner surface coated with a multiple cavity controlled transmissioncoating and an outer surface coated with a hydrophilic coating, and asecond pane having an outer surface coated with a transparent conductivecoating in accordance with certain embodiments of the invention.

FIG. 7 is a schematic cross-sectional, broken-away view of a laminatedglass assembly comprising two panes laminated together with a multiplecavity controlled transmission coating on an inner surface of one of thepanes in accordance with still other embodiments of the invention.

FIG. 8 is a schematic end view of a sputtering chamber that has utilityin certain methods of the invention.

SUMMARY

In some embodiments, the invention provides a multiple-pane insulatingglazing unit having a between-pane space. The insulating glazing unitcomprises a pane having a desired surface coated with a low-emissivitycoating. The desired surface of the pane is exposed to the notedbetween-pane space. The low-emissivity coating comprises, in sequencemoving outwardly from the desired surface of the pane, a dielectric basecoat comprising oxide film, nitride film, or oxynitride film, a firstinfrared-reflective layer, a first nickel-aluminum blocker layer incontact with the first infrared-reflective layer, a first dielectricspacer coat comprising an oxide film in contact with the firstnickel-aluminum blocker layer, a second infrared-reflective layer, asecond nickel-aluminum blocker layer in contact with the secondinfrared-reflective layer, a second dielectric spacer coat comprising anoxide film in contact with the second nickel-aluminum blocker layer, athird infrared-reflective layer, a third nickel-aluminum blocker layerin contact with the third infrared-reflective layer, and a dielectrictop coat comprising an oxide film in contact with the thirdnickel-aluminum blocker layer. In the present embodiments, themultiple-pane insulating glazing unit has a solar heat gain coefficientof less than 0.2.

Certain embodiments of the invention provide a multiple-pane insulatingglazing unit having a between-pane space. The glazing unit includes apane having a desired surface coated with a low-emissivity coating. Thedesired surface of the pane is exposed to the noted between-pane space.The low-emissivity coating comprises, in sequence moving outwardly fromthe desired surface of the pane, a dielectric base coat comprising oxidefilm, nitride film, or oxynitride film, a first infrared-reflectivelayer, a first nickel-aluminum blocker layer in contact with the firstinfrared-reflective layer, a first dielectric spacer coat comprising anoxide film in contact with the first nickel-aluminum blocker layer, asecond infrared-reflective layer, a second nickel-aluminum blocker layerin contact with the second infrared-reflective layer, a seconddielectric spacer coat comprising an oxide film in contact with thesecond nickel-aluminum blocker layer, a third infrared-reflective layer,a third nickel-aluminum blocker layer in contact with the thirdinfrared-reflective layer, and a dielectric top coat comprising an oxidefilm in contact with the third nickel-aluminum blocker layer. In thepresent embodiments, the first, second, and third infrared-reflectivelayers have a combined thickness of between 375 angstroms and 650angstroms in combination with the second and third nickel-aluminumblocker layers each being between 75% and 400% thicker than the firstnickel-aluminum blocker layer.

Preferably, the multiple-pane insulating glazing unit of the presentembodiments has a visible transmittance of between 0.3 and 0.5.

Some embodiments of the invention provide a laminated glass assemblycomprising first and second glass panes, a polymer interlayer, and acontrolled transmission coating. The polymer interlayer is sandwichedbetween the first and second glass panes. The controlled transmissioncoating is on an internal surface of the first pane such that thecontrolled transmission coating is located between the first pane andthe polymer interlayer. The controlled transmission coating comprises,in sequence moving away from the internal surface of the first pane, adielectric base coat comprising oxide film, nitride film, or oxynitridefilm, a first infrared-reflective layer, a first nickel-aluminum blockerlayer in contact with the first infrared-reflective layer, a firstdielectric spacer coat comprising an oxide film in contact with thefirst nickel-aluminum blocker layer, a second infrared-reflective layer,a second nickel-aluminum blocker layer in contact with the secondinfrared-reflective layer, a second dielectric spacer coat comprising anoxide film in contact with the second nickel-aluminum blocker layer, athird infrared-reflective layer, a third nickel-aluminum blocker layerin contact with the third infrared-reflective layer, and a dielectrictop coat comprising an oxide film in contact with the thirdnickel-aluminum blocker layer. Preferably, the first, second, and thirdinfrared-reflective layers each comprises silver.

DETAILED DESCRIPTION

The following detailed description is to be read with reference to thedrawings, in which like elements in different drawings have likereference numerals. The drawings, which are not necessarily to scale,depict selected embodiments and are not intended to limit the scope ofthe invention. Skilled artisans will recognize that the examplesprovided herein have many useful alternatives that fall within the scopeof the invention.

The present invention provides controlled transmission coatings thatinclude at least one nickel-aluminum film. The nickel-aluminum film hasutility in a wide variety of controlled transmission coatings.Particular utility is provided for silver-based low transmissioncoatings (i.e., coatings that have a visible transmission of less than50% and include at least one silver-containing infrared-reflectivefilm). In some embodiments, the controlled transmission coating is aheat-treatable (or heat treated, e.g., tempered) low-emissivity coating.

The invention provides a controlled transmission coating on a substrate(e.g., a glazing sheet). Substrates suitable for use in connection withthe present invention include the substrate class comprising flat,sheet-like substrates. A substrate of this nature has two opposed majorsurfaces (or “faces”). In most cases, the substrate will be a sheet oftransparent material (i.e., a transparent sheet). The substrate may be asheet of glass. One type of glass that is commonly used in manufacturingglass articles (e.g., insulating glass units) is soda-lime glass.Soda-lime glass will be a preferred substrate in many cases. Of course,other types of glass can be used as well, including those generallyreferred to as alkali-lime-silicon dioxide glass, phosphate glass, andfused silicon dioxide. If desired, tinted glass can be used. In somecases, the substrate will comprise a polymeric (e.g., plastic) materialthat is transparent or translucent.

Substrates of various sizes can be used in the present invention.Commonly, large-area substrates are used. Certain embodiments involve asubstrate having a length and/or width of at least 0.5 meter, preferablyat least 1 meter, perhaps more preferably at least 1.5 meters (e.g.,between 2 meters and 4 meters), and in some cases at least 3 meters. Insome embodiments, the substrate is a jumbo glass sheet having a lengthand/or width that is between 3 meters and 10 meters, e.g., a glass sheethaving a width of about 3.5 meters and a length of about 6.5 meters.

Substrates of various thicknesses can be used in the present invention.For example, the substrate (which can optionally be a glass sheet) canhave a thickness in the range of from 1-14 mm, such as from 2-14 mm.Some embodiments involve a substrate with a thickness of between 2 mmand 5 mm, such as between 2.3 mm and 4.8 mm, and perhaps more preferablybetween 2.5 mm and 4.8 mm. In one example, a sheet of glass (e.g.,soda-lime glass) with a thickness of about 3 mm is used.

FIG. 1 shows one embodiment of the invention involving a multiple-cavity(or “triple-IR-layer-type”) controlled transmission coating, i.e., alow-emissivity coating or other controlled transmission coating based onthree infrared-reflective layers. Low-emissivity coatings are well knownin the present art. Therefore, given the present teaching as a guide,those skilled in this field would be able to readily select and vary theprecise nature (e.g., composition, thickness, and deposition process) ofthe various films in the present coating to accommodate differentapplications. Thus, the film stacks described herein are merelyexemplary.

In the embodiment of FIG. 1, the multiple-cavity controlled transmissioncoating 20 has three infrared-reflective layers 50, 150, 250. Theselayers 50, 150, 250 can be formed of any desired infrared-reflectivematerial. Silver is the most commonly used infrared-reflective material.However, gold, copper, or another infrared-reflective material can beused. Likewise, alloys or mixtures of these materials can be used. Inmany cases, it will be preferable to form these layers 50, 150, 250 ofsilver or silver-containing film. For example, one or each of theselayers 50, 150, 250 can optionally be formed of silver combined with asmall amount (e.g., about 5% or less) of gold, platinum, or tin. Thoseskilled in the present art may prefer to use other known types ofsilver-containing films. Moreover, if desired, one or more (e.g., each)of these layers 50, 150, 250 may comprise a transparent conductive oxidefilm (e.g., ITO) or an electrically conductive nitride film (e.g., TiN).

The first infrared-reflective layer 50 preferably has a thickness ofbetween 50 and 200 angstroms. A lesser or greater thickness, however,may be suitable for certain applications. Typically, it is advantageousto select the thicknesses and materials of the infrared-reflective films50, 150, 250 so as to provide infrared reflectance values of above 60%,and more preferably above 85% (in the 3 to 10 micron range). In somecases, the coating 20 is designed to achieve infrared reflectance valuesas close as possible to 100%, while still providing the desired level ofvisible transmission. In certain embodiments, the firstinfrared-reflective layer 50 comprises silver at a thickness of from 90and 170 angstroms. As one example, silver at a thickness of about 110angstroms can be used.

Oxygen is preferably prevented from coming into reactive contact withthe infrared-reflective film. Thin silver film, for example, is known tobe highly sensitive to all forms of energy, and since it is not wettingdielectric surfaces, it may disintegrate and form islands. Exposure toimpact by energetic ions (e.g., of oxygen), which can originate from thesputtering process in applying an immediately overlying antireflectionfilm, can damage the fresh silver film. To prevent this, a thin metalfilm (sometimes referred to as a “sacrificial layer” or “blocker layer”)is coated on top of the silver film with low power. This forms astronger bond to the silver film and keeps the silver material fromde-wetting and clustering. To bond this thin metal film strongly to theimmediately overlying dielectric layer, part of the metal blocker layercan be reacted (e.g., oxidized) to form a strong bond with theimmediately overlying dielectric layer. Preferably, there is nowell-defined, sharp (e.g., “discrete”) interface between the metallicand reacted portions of the blocker layer. In the past, some blockerlayers were made by sputtering titanium metal on top of a silver layer,and the titanium was partially reacted (e.g., oxidized) by residualgases or so called crosstalk from adjacent reactive sputtering stationsthat are not perfectly controlled. As the power and sputtering speedwere low (for depositing the thin blocker layer), the degree of reaction(e.g., oxidation) and the thickness of the reacted portion was not wellcontrolled. The thickness of the remaining metallic part will impactboth the coating's absorption of light and the mechanical cohesion atthe interface, as well as influencing mechanical and chemical propertiesof the final product.

The present nickel-aluminum blocker film is particularly well suited forsimultaneously: i) preventing oxygen from reaching and reacting with anunderlying metallic infrared-reflective film, ii) adhering strongly toboth an underlying metallic infrared-reflective film (in someembodiments, due to a non-reacted nickel component) and an overlyingoxide film (e.g., due to its more easily reacted aluminum component),iii) providing the coating with particularly good mechanical durability,iv) providing the coating with exceptional moisture resistance, and v)enabling good control over optical properties (e.g., visibletransmission) of the coating. It has been discovered that with thepresent Ni/Al blocker films, after completing the sputtering process andany subsequent heat-treatment in air, the targeted amount of remainingnickel metal is largely independent from the minute, difficult tocontrol changes in coater vacuum conditions.

Aluminum reacts readily with oxygen, particularly at elevatedtemperatures, to form aluminum oxide (i.e., “alumina”). Nickel tends tobe less reactive with oxygen. It is therefore postulated that when anickel-aluminum film is deposited directly over (i.e., so as to be incontact with) an underlying silver layer and directly under (i.e., so asto be in contact with) an overlying oxide layer, aluminum in an upperportion of the blocker film becomes oxidized or more oxidized (e.g.,fully oxidized), while nickel in a lower portion of the layer remainsmetallic or in substoichiometric form. Preferably, nickel at theinterface with an underlying silver film remains metallic, as does thesilver film itself. This appears to provide an exceptional bond withboth the underlying metallic film and the overlying oxide film. Whilethe foregoing mechanism is believed to contribute to the exceptionalproperties achieved by the present coatings, this explanation is notintended to be binding.

The nickel-aluminum blocker film is capable of chemically reacting with,and thus capturing, oxygen to form oxides of the nickel-aluminum. Thenickel-aluminum film may also suppress the mobility of silver atomsduring any heat-treatment. In such cases, the nickel-aluminum film mayhelp maintain a continuous silver film.

It is surmised that when a film stack including oxide and/or nitridefilms is heated to glass tempering temperatures, the excess oxygenand/or nitrogen in these films may become mobile, and at such hightemperatures are very reactive. It is thought that such highly reactiveoxygen and/or nitrogen can be captured by the nickel-aluminum blockerfilm(s). As described in U.S. Pat. No. 6,919,133, conventional glasstempering is commonly performed in an oxidizing atmosphere (e.g., air).The teachings of this '133 Patent are hereby incorporated herein insofaras they describe (see Example 1) a conventional glass tempering process,wherein glass is treated at elevated temperatures reaching about 734 C.It is also surmised that reactive oxygen from the atmosphere maypenetrate the film stack during tempering. In such cases, this reactiveoxygen may be captured by the nickel-aluminum blocker film(s) as well.

In the embodiment of FIG. 1, a first nickel-aluminum blocker film 80 isformed upon the first infrared-reflective film 50. In some cases, thenickel-aluminum film is deposited as a metallic (i.e., elemental metal)film. Such film can be sputtered, for example, from one or more metallic(e.g., alloy) targets onto the infrared-reflective film 50 in an inertatmosphere (e.g., argon). If desired, one or more nickel-aluminumtargets can be sputtered. Alternatively, a metallic aluminum target canbe co-sputtered with a nickel alloy target. The thus coated substratemay then be conveyed into a subsequent oxygen-containing sputtering zone(e.g., where a subsequent oxide film is deposited upon thenickel-aluminum film). As a result of this exposure, the nickel-aluminumfilm will typically become at least partially oxidized. Preferably, anouter portion of this layer (or at least aluminum therein) will becomeoxidized, while an inner portion (or at least nickel therein) remainsmetallic. Providing metallic nickel in the inner portion can impartadditional absorption of visible radiation, thus facilitatingparticularly good control over visible transmission. This isadvantageous for providing the coating with a low level of visibletransmission. The discussion in this paragraph applies for eachnickel-aluminum blocker film in the coating.

In certain embodiments, the nickel-aluminum film is deposited as asub-oxide (i.e., substoichiometric) film. If desired, thenickel-aluminum film, as deposited, can be substoichiometric across theentire thickness of the film. In some cases, a sub-oxide nickel-aluminumfilm is deposited by sputtering one or more sub-oxide nickel-aluminumtargets onto the first infrared-reflective film 50 in an inertatmosphere (e.g., argon). If desired, some oxygen, nitrogen, or both canbe used in the sputtering atmosphere, but in an amount small enough todeposit the film as a sub-oxide. When provided, the sub-oxidenickel-aluminum target(s) can optionally further include titaniumsub-oxide, e.g., TiO_(x), where x is less than 2. In other cases, asub-oxide nickel-aluminum film is deposited by sputtering one or moremetallic nickel-aluminum targets onto the first infrared-reflective film50 in an oxidizing atmosphere wherein the amount and/or reactivity ofoxygen is controlled to deposit the film as a sub-oxide. In still othercases, separate targets formed respectively of nickel alloy and metallicaluminum are co-sputtered in a sub-oxidizing atmosphere (wherein theamount and/or reactivity of oxygen are controlled to deposit the film asa sub-oxide). If desired, one or each of the co-sputtered targets mayinclude titanium. Regardless of which deposition method is used, thethus coated substrate may then be conveyed into a subsequentoxygen-containing sputtering zone (e.g., where a subsequent oxide filmis deposited upon the sub-oxide nickel-aluminum film). As a result ofthis exposure, the sub-oxide film will become further oxidized.Preferably, an outer portion of this film (or at least aluminum therein)will become more oxidized (e.g., fully oxidized), while an inner portion(or at least nickel therein) remains less oxidized (e.g.,substoichiometric). It has been discovered that the specific combinationof nickel and aluminum, including this combination in sub-oxide form,can provide particularly good durability. This can be especiallyadvantageous for laminated glass embodiments (e.g., where both thecontrolled transmission coating and a polymer interlayer are sandwichedbetween two glass panes, such that there is no air space between the twopanes). The discussion in this paragraph applies for eachnickel-aluminum blocker film in the coating.

It is to be understood that the term “nickel-aluminum” is used herein torefer to any compound that includes at least some nickel and at leastsome aluminum. Included in this definition is any alloy or mixturecomprising both nickel and aluminum, whether metallic (i.e., elementalmetal) or in the form of an oxide, a nitride, an oxynitride, etc., andoptionally including one or more other desired materials. In someembodiments, nickel and aluminum are the only metals dispersed along theentire thickness of the nickel-aluminum blocker film. For example, thenickel-aluminum film can optionally be free of (i.e., devoid of) metalsother than nickel and aluminum. If desired, the nickel-aluminum canconsist essentially of (or consist of) metallic nickel and metalaluminum, optionally together with reaction products (e.g., oxides,nitrides, oxynitrides, etc.) thereof. In some cases, the nickel-aluminumconsists essentially of (or consists of) nickel, aluminum, and oxygenand/or nitrogen. The discussion in this paragraph applies for eachnickel-aluminum blocker film in the coating.

Preferably, the nickel-aluminum blocker film contains (and/or isdeposited as film containing) more than 7.5% aluminum by weight.Additionally or alternatively, the film can optionally contain (and/orbe deposited as film containing) less than 30% aluminum by weight. Thus,the blocker film can advantageously contain (and/or be deposited as filmcontaining) aluminum at a weight percentage of between 7.5% and 30%,such as between 7.5% and 25%, or between 7.5% and 15%, e.g., about 10%,with the remainder optionally being nickel. In one embodiment, thenickel-aluminum film is deposited as film containing about 90% nickeland about 10% aluminum. In embodiments where the nickel-aluminum filmcomprises oxygen, nitrogen, or both, the foregoing percentages are on ametal-only basis. The discussion in this paragraph applies for eachnickel-aluminum blocker film in the coating.

In certain embodiments, the nickel-aluminum film also includes titanium.In such cases, the relative amounts of nickel, aluminum, and titaniumcan be varied depending upon the particular application, the propertiesdesired, etc. When provided, titanium can be present in thenickel-aluminum film in metallic form, stoichiometric oxide form, and/orsub-oxide form. The discussion in this paragraph applies for eachnickel-aluminum blocker film in the coating.

In certain embodiments, the first blocker film 80 is a single layerblocker coating. In some cases, it is deposited in metallic form, inwhich case it may optionally consist essentially of (or consist of)nickel and aluminum as deposited, or it may consist essentially of (orconsist of) nickel, aluminum and titanium as deposited. In such cases,the first nickel-aluminum blocker film 80 preferably is sandwicheddirectly between (i.e., so as to contact both) an underlyinginfrared-reflective film (e.g., a silver layer) and an overlying oxidefilm. In other embodiments, the first nickel-aluminum blocker film 80 isdeposited directly over the first infrared-reflective layer 50, atitanium-containing film is deposited directly over the firstnickel-aluminum blocker film, and a transparent dielectric film (e.g.,an oxide film) is deposited directly over the titanium-containing film.This can optionally be the case for any one or more (e.g., all) blockerfilms in the coating. The titanium-containing film can be a titaniumsub-oxide film, a titanium dioxide film, or an outer portion of the filmcan comprise TiO₂ while an inner portion comprises titanium sub-oxide,metallic titanium, or both. The titanium-containing film can optionallyalso contain nickel and aluminum.

In still other embodiments, a titanium-containing film is depositeddirectly over the first infrared-reflective layer, a firstnickel-aluminum blocker film is deposited directly over thetitanium-containing film, and a transparent dielectric (e.g., an oxidefilm) is deposited directly over the first nickel-aluminum blocker film.Here again, this can optionally be the case for any one or more (e.g.,all) blocker films in the coating. The titanium-containing film can be atitanium sub-oxide film or a titanium dioxide film, or an outer portionof the film can be TiO₂ while an inner portion is titanium sub-oxide.The titanium-containing film can optionally also contain nickel andaluminum.

The first nickel-aluminum blocker film 80 has a thickness designed toprotect the underlying first infrared-reflective film 50 and to controlthe optical properties (e.g., visible transmission) desired for thecoated substrate. Generally, the thickness of the first nickel-aluminumblocker film 80 is in the range of about 10-90 angstroms, such asbetween 10 angstroms and 60 angstroms.

In certain embodiments, the thickness of the first nickel-aluminumblocker film 80 is selected such that following a desired heat treatment(e.g., glass tempering) and the associated conversion of some of thealuminum, and possibly some of the nickel, to an oxide, there remains aportion (e.g., the innermost portion) of the nickel-aluminum film thatis not significantly oxidized. This inner portion may be metallic, or atleast substantially non-oxidized. The blocker layer thickness, forexample, can be selected such that the innermost portion remainsmetallic. In such cases, the unreacted portion will typically be (orinclude) that portion of the nickel-aluminum layer that is contiguous toa directly underlying infrared-reflective film.

In the embodiment of FIG. 1, the first nickel-aluminum blocker film 80is positioned over the outer face (i.e., the face oriented away from thesubstrate) of the first infrared-reflective film 50. Preferably, thisnickel-aluminum blocker film 80 is positioned directly over (i.e., is incontact with) the underlying first infrared-reflective film 50. Thediscussion in this paragraph applies for each nickel-aluminum blockerfilm in the coating.

With continued reference to the embodiment of FIG. 1, an antireflectivebase coat 30 is formed upon one of the two major surfaces of thesubstrate 10. The base coat 30 includes one or more transparentdielectric films. It is to be understood that the term “transparentdielectric” is used herein to refer to any non-metallic (e.g., neither apure metal nor a metal alloy) compound film that includes any one ormore metals and has a visible transmission of at least 50% when providedat a thickness of 300 angstroms or less. Included in this definitionwould be any film of metal oxide, metal nitride, metal oxynitride, metalcarbide, metal sulfide, metal boride, or any combination thereof havingvisible transmission in the specified range. Further, the term “metal”should be understood to include all metals and semi-metals (i.e.,metalloids). Preferably, each transparent dielectric film is an oxide,nitride, or oxynitride.

The antireflective base coat 30 preferably has an overall thickness ofbetween 150 angstroms and 600 angstroms, and more preferably between 200angstroms and 600 angstroms, such as from 250 to 550 angstroms. The basecoat 30 may comprise one or more transparent dielectric materials. Forexample, a wide variety of metal oxides may be used, including oxides ofzinc, tin, indium, bismuth, titanium, hafnium, zirconium, and alloys andmixtures thereof. While metal oxides are sometimes preferred due totheir ease and low cost of application, metal nitrides (e.g., siliconnitride) and oxynitrides (e.g., silicon oxynitride) can also be usedadvantageously. Those skilled in the present art would be able toreadily select other materials that could be used for the base coat 30.

The base coat 30 in the embodiment of FIG. 1 is depicted as being asingle film. However, the base coat 30 can comprise a plurality offilms, if so desired. For example, the base coat 30 can comprise twoseparate films, optionally formed of different transparent dielectricmaterials. In one example, the base coat 30 comprises a first filmcomprising silicon dioxide having a thickness of about 230 angstromsfollowed by a second film comprising zinc tin oxide having a thicknessof about 195 angstroms.

The composition of the base coat 30 can be varied as desired. However,it is generally preferred that at least a thin film comprising zincoxide be applied as the outermost portion (i.e., the portion farthestaway from the substrate) of the base coat. This is believed to enhancethe quality of the film stack, at least if the overlyinginfrared-reflective layer 50 is formed of silver. Zinc oxide-based filmshave been found to provide a good foundation for the nucleation ofsilver. Thus, it is preferable either to form the whole base coat 30 offilm comprising zinc oxide or to form it with two or more films whereinthe outermost film comprises zinc oxide.

As noted above, it is contemplated that the antireflective base coat 30will comprise two or more films in certain embodiments. A variety offilm stacks are known to be suitable for use as the antireflective basecoat of a “triple-IR-layer-type” low-emissivity coating. For example,the first film (i.e., the film nearest the substrate) may be tin oxide,titanium dioxide, silicon nitride, or an alloy or mixture of zinc oxide,such as an alloy or mixture of zinc oxide and bismuth oxide, tin oxide,or indium oxide. As noted above, the second film preferably compriseszinc oxide (such as pure zinc oxide, zinc tin oxide, or zinc aluminumoxide), at least if the overlying infrared-reflective film 50 is formedof silver. While the relative thicknesses of these two films can bevaried as desired, the combined thickness of both films is preferablybetween 150 angstroms and 600 angstroms, such as from 250 to 550angstroms. Those skilled in the present art would be able to readilyselect a variety of other suitable film stacks to use as theantireflective base coat 30.

In the embodiment of FIG. 1, the second illustrated film 50 is the firstinfrared-reflective layer 50, and the third illustrated film 80 is thefirst nickel-aluminum blocker film. Both of these layers 50, 80 havealready been discussed.

With continued reference to FIG. 1, a first dielectric spacer coat 190is positioned outwardly from (i.e., further from the substrate than) thefirst infrared-reflective layer 50, e.g., on the first blocker film 80.In its simplest form, this spacer coat 190 consists of a single layer ofa transparent dielectric material. For example, a single transparentdielectric film (e.g., zinc tin oxide) having a thickness of about450-1,200 angstroms can be used.

Alternatively, two or more separate transparent dielectric films can bepositioned between the first and second infrared-reflective layers 50,150. In such cases, these films preferably have a combined thickness ofabout 450-1,200 angstroms.

Thus, in a controlled transmission coating having threeinfrared-reflective films 50, 150, 250, the innermostinfrared-reflective film 50 preferably is directly followed by, movingoutwardly, a contiguous sequence of a nickel-aluminum blocker film 80and a metal oxide film (e.g., zinc tin oxide). If desired, one or moreadditional films can be provided between the metal oxide film and thesecond infrared-reflective film 150.

FIG. 1 depicts a “triple-IR-type” low-emissivity coating. Thus, thecoating includes second and third infrared-reflective films 150, 250.The materials useful in forming the first infrared-reflective film 50are also useful in the forming second and third infrared-reflectivefilms 150, 250. In most cases, all three infrared-reflective films 50,150, 250 will be formed of the same material, although this is not arequirement. Preferably, these films 50, 150, 250 are silver orsilver-containing films, with the third (and outermost) IR-reflectivefilm 250 being thicker than the second IR-reflective film 150, while thesecond IR-reflective film 150 is thicker than the first (and innermost)IR-reflective film 50. One example provides a first infrared-reflectivelayer 50 of silver at a thickness in the range of 100-150 angstroms, incombination with a second infrared-reflective layer 150 of silver at athickness in the range of 150-180 angstroms, and a thirdinfrared-reflective layer 250 of silver at a thickness in the range of155-190 angstroms.

A second nickel-aluminum film 180 can advantageously be provided overthe second infrared-reflective film 150. This nickel-aluminum film 180can be of the nature described above relative to the first blocker film80. The second nickel-aluminum layer 180 can optionally be formeddirectly upon the underlying infrared-reflective film 150. The thicknessof the second nickel-aluminum film 180 is preferably in the range ofabout 10-90 angstroms. Thus, in some embodiments, the first and secondblocker films 80, 180 are nickel-aluminum layers, each deposited at athickness of about 10-90 angstroms. In other embodiments, the coatinghas only one nickel-aluminum blocker film. In such embodiments, thecoating may include two other blocker films of a different composition.

In certain preferred embodiments, the coating 20 includes two blockerfilms that have different thicknesses. For example, one of thenickel-aluminum blocker films can be at least 50% thicker than, morethan 75% thicker than, or even more than twice as thick as, another ofthe nickel-aluminum blocker films. In some cases, three nickel-aluminumblocker films 80, 180, 280 are provided such that a first 80 of thethree nickel-aluminum blocker films is located closer to the glazingsheet than is a second 180 of the two nickel-aluminum blocker films,while the second 180 of the nickel-aluminum blocker films is locatedcloser to the glazing sheet than is the third nickel-aluminum blockerfilm 280, and the second 180 or third 280 nickel-aluminum blocker filmis more than 50% thicker than, or more than 75% thicker than, the firstnickel-aluminum blocker film 80. In certain embodiments, each of thesecond 180 and third 280 nickel-aluminum blocker films is more than 50%thicker than, more than 75% thicker than, or even more than twice asthick as, the first nickel-aluminum blocker film 80.

If desired, a nickel-aluminum layer 180′ can be positioned directlybeneath the second infrared-reflective layer 150. Additionally oralternatively, a nickel-aluminum layer can optionally be positioneddirectly beneath the first infrared-reflective layer 50, directlybeneath the third infrared-reflective layer 250, or both. Reference ismade to FIG. 2, which is discussed below.

With continued reference to FIG. 1, a second dielectric spacer coat 290is positioned outwardly from (i.e., further from the substrate than) thesecond infrared-reflective layer 150, e.g., on the second blocker film180. In its simplest form, this spacer coat 290 consists of a singlelayer of any desired transparent dielectric material. For example, asingle transparent dielectric film (e.g., zinc tin oxide) having athickness of about 400-1,200 angstroms can be used.

Alternatively, two or more separate transparent dielectric films can bepositioned between the second and third infrared-reflective layers 150,250. In such cases, these films preferably have a combined thickness ofabout 400-1,200 angstroms.

As noted above, the coating of FIG. 1 includes a thirdinfrared-reflective film 250. The materials useful in forming the firstand second infrared-reflective films 50, 150 are also useful in theforming the third infrared-reflective film 250. While not required, allthree infrared-reflective films 50, 150, 250 will typically be formed ofthe same material. Preferably, these films 50, 150, 250 are silver orsilver-containing films, with the third (and outermost) IR-reflectivefilm 250 being thicker than the second IR-reflective film 150, while thesecond IR-reflective film is thicker than the first (and innermost)IR-reflective film 50. One example provides a first infrared-reflectivelayer 50 of silver at a thickness in the range of 100-150 angstroms, incombination with a second infrared-reflective layer 150 of silver at athickness in the range of 150-180 angstroms, and a thirdinfrared-reflective layer 250 of silver at a thickness in the range of155-190 angstroms.

A third nickel-aluminum layer 280 can advantageously be provided overthe third infrared-reflective film 250. This nickel-aluminum layer 280can be of the nature described above. For example, this layer 280 canoptionally be formed directly upon the underlying infrared-reflectivefilm 250. The thickness of the second nickel-aluminum layer 280 ispreferably in the range of about 10-90 angstroms. Thus, in someembodiments, the first, second, and third blocker films 80, 180, 280 arenickel-aluminum layers, each deposited at a thickness of about 10-90angstroms. In other embodiments, the coating has only one or twonickel-aluminum blocker films. In such embodiments, the coating mayinclude one or two other blocker films of a different composition.

In the embodiment of FIG. 1, an outer film region 130 is positionedoutwardly from the third infrared-reflective film 250 (e.g., directlyupon the third blocker film 280). The exact nature of the outer filmregion 130 can be varied as desired. In its simplest form, the outerfilm region 130 consists of a single transparent dielectric film. A widevariety of metal nitrides (e.g., silicon nitride), oxynitrides (e.g.,silicon oxynitride), or metal oxides (e.g., oxides of zinc, tin, indium,bismuth, titanium, hafnium, zirconium, and alloys and mixtures thereof)can be used as the outermost layer of a low-emissivity coating. In oneembodiment, the outer film region 130 is a single film (e.g., siliconnitride, tin oxide, or zinc tin oxide) having a thickness of betweenabout 100 angstroms and about 600 angstroms, e.g., between 120 angstromsand 550 angstroms.

It may be preferable to use an outer film region 130 comprising aplurality of separate layers. For example, the outer film region 130 cancomprise two separate layers. A first outer layer can be depositeddirectly upon the third blocker film 180. The first outer layer can beformed of any desired transparent dielectric material. For example, thislayer can advantageously be formed of zinc tin oxide. The thickness ofthe first outer layer is preferably between 100 and 350 angstroms, andmore preferably between 150 and 300 angstroms, such as about 270angstroms. A second outer layer can be deposited directly upon the firstouter layer. While this layer can be formed of any desired transparentdielectric material, it is preferably formed of a chemically-durablematerial, such as silicon nitride. The thickness of the second outerlayer is preferably between 100 and 400 angstroms, such as between 150and 300 angstroms. In one example, the first outer layer is formed ofzinc tin oxide at a thickness of about 270 angstroms, and the secondouter layer is formed of silicon nitride at a thickness of about 260angstroms. More generally, a variety of film stacks are known to besuitable for use as the outer film region of a “triple-IR-layer-type”low-emissivity coating.

FIG. 2 illustrates an embodiment wherein two nickel-aluminum films arepositioned respectively under and over each infrared-reflective film inthe coating. In this embodiment, the first infrared-reflective film 50is sandwiched directly between (i.e., so as to contact) twonickel-aluminum films 80, 80′, the second infrared-reflective film 150is sandwiched directly between two nickel-aluminum films 180, 180′, andthe third infrared-reflective film 250 is sandwiched directly betweentwo nickel-aluminum films 280, 280′. Sandwiching an infrared-reflectivefilm (e.g., one formed of silver) directly between two nickel-aluminumlayers may be advantageous, for example, in cases where it is desirableto provide particularly good protection for the infrared-reflectivefilm, where particularly high shading ability is desired, or where it isdesirable to provide particularly good mechanical durability, chemicaldurability, or both. When provided, the nickel-aluminum films 80′, 180′,280′ beneath the infrared-reflective films 50, 150, 250 can optionallybe thinner than the nickel-aluminum films 80, 180, 280 over theinfrared-reflective films 50, 150, 250. Additionally or alternatively,the nickel-aluminum films 80′, 180′, 280′ beneath theinfrared-reflective films 50, 150, 250 can optionally be oxidized to agreater extent than the nickel-aluminum layers 80, 180, 280 over theinfrared-reflective films 50, 150, 250. For example, the nickel-aluminumfilm directly under an infrared-reflective layer may be oxidized (e.g.,may comprise sub-oxide film) over its entire thickness, while thenickel-aluminum film directly over that infrared-reflective layer mayhave only an outer portion that is oxidized (the rest may be metallic).Thickness arrangements and/or relative oxidation states of this naturemay be provided to establish high shading ability, without morereduction in visible transmission than is desired, while simultaneouslyproviding particularly good mechanical durability, chemical durability,or both.

Thus, it will be appreciated that certain embodiments of the inventionprovide a controlled transmission coating having threeinfrared-reflective layers, and wherein there is at least one contiguoussequence of, moving outwardly, a zinc tin oxide film, a silver orsilver-containing film, and a nickel-aluminum film. The silver orsilver-containing film in the sequence is positioned directly over thezinc tin oxide film and directly beneath the nickel-aluminum layer.Further, an oxide film preferably is positioned directly over thenickel-aluminum layer in the noted contiguous sequence. It will beappreciated that the present coating 20 preferably has three suchcontiguous sequences.

One group of embodiments provides a substrate 10 bearing the controlledtransmission coating 20. The substrate 10 has a first surface 12 and asecond surface 14. The controlled transmission coating 20 is on thesecond surface 14. In some cases, the coated substrate 10 is amonolithic pane. Typically, the coated second surface 14 will bedestined to be an internal surface facing a between-pane space 800 of amultiple-pane insulating glazing unit 110, while the first surface 12 isdestined to be an external surface exposed to an outdoor environment.

Thus, certain embodiments provide a multiple-pane insulating glazingunit 110 having a substrate 10 coated with a controlled transmissioncoating 20. FIG. 3 is a partially broken-away schematic cross-sectionalside view of a multiple-pane insulating glazing unit 110 in accordancewith one such embodiment. In FIG. 3, the insulating glazing unit 110 hasan exterior pane 10 and an interior pane 10′ separated by a between-panespace 800. A spacer 900 (which can optionally be integral to a sash) isprovided to separate the panes 10 and 10′. The spacer can be secured tothe interior surfaces of each pane using one or more beads of adhesive700. In some cases, an end sealant (not shown) is also provided. In theillustrated embodiment, the exterior pane 10 has an external surface 12and an internal surface 14.

With respect to embodiments involving an IG unit, the “first” (or “#1”)surface 12 is commonly be intended to be exposed to an outdoorenvironment. For example, when an IG unit is mounted on an exterior wallof a building, it is the #1 surface that radiation from the sun firststrikes. The external surface of such an outboard pane is the so-calledfirst surface. Moving from the #1 surface toward the interior of thebuilding, the next surface is the “second” (or “#2”) surface 14. Thus,the internal surface of the outboard pane is the so-called secondsurface. Moving further toward the interior of the building, the nextsurface is the “third” (or “#3”) surface 16, followed by the “fourth”(or “#4”) surface 18. This convention is carried forward for IG unitshaving more than four major pane surfaces.

In the embodiment of FIG. 3, the second surface 14 of the first pane 10bears the controlled transmission coating 20. The second pane 10′ alsohas two opposed major surfaces 16, 18. The IG unit 110 can be mounted ina frame (e.g., a window frame) such that the first surface 12 of thefirst pane 10 is exposed to an outdoor environment. In some embodimentsof this nature, surface 18 of the second pane 10′ is exposed to aroom-side environment (e.g., a temperature controlled environment)inside a home or other building. Internal surfaces 14 and 16 are bothexposed to the between-pane space 800 of the illustrated insulatingglazing unit. While surface 14 bears the controlled transmission coating20 in FIG. 3, it is to be understood that surface 16 can alternativelyor additionally bear such a coating.

In some embodiments, a hydrophilic and/or photocatalytic coating 40(hereinafter, a “hydrophilic” coating) can also be provided on the #1surface of the IG unit 110. Reference is made to FIGS. 4 and 6. Ifdesired, the hydrophilic coating can alternatively be provided on theother external surface (e.g., the #4 surface) of the IG unit 110. Insome cases, the hydrophilic film 40 comprises titania and has athickness of from 20 angstroms to 175 angstroms. In some embodiments,the #1 surface has a first hydrophilic coating 20, while the otherexternal surface (e.g., the #4 surface) of the IG unit 100 has a secondhydrophilic coating. Useful hydrophilic coatings are described in U.S.Pat. Nos. 7,294,404, 7,604,865, 7,713,632, 7,782,296, 7,862,309,7,923,114 and 8,092,660, the salient teachings (i.e., the teachingsconcerning the hydrophilic coating) of each of which are herebyincorporated herein by reference.

When provided, the hydrophilic coating 40 can optionally further includea transparent conductive film. In such cases, the coating 40 cancomprise a hydrophilic film, optionally comprising titania, over atransparent conductive film (optionally comprising both indium and tin).In some cases, the hydrophilic film comprising titania has a thicknessof from 20 angstroms to 175 angstroms. In one example, the hydrophiliccoating 40 (shown in FIGS. 4 and 6) has the following structure:glass/SiO₂ 100 Å/indium-tin metal 790 Å/Si₃N₄ 125 Å/silicon oxynitride750 Å/TiO₂ 75 Å. In another example, the hydrophilic coating 40 has thefollowing structure: glass/silica 35 Å/indium tin oxide 1200 Å/siliconnitride 95 Å/silicon oxynitride 805 Å/TiO₂ 60 Å.

As noted above, the multiple-pane insulating glazing unit 110 has twoopposed, external pane surfaces. In the double glazing embodiments shownin FIGS. 3-6, these external surfaces are the #1 and #4 surfaces. The IGunit 110 can alternatively be a triple glazing, in which case the twoexternal surfaces will be the #1 and #6 surfaces. In certainembodiments, at least one of the two external surfaces of the IG unit110 is coated with a transparent conductive film 60. In the embodimentof FIG. 5, for example, the #4 surface of the IG unit 110 has atransparent conductive film 60. The transparent conductive film 60 canadvantageously comprise both indium and tin. It can, for example, be anindium-tin oxide film. In other cases, it can be a metallic film ofindium and tin. In one example, the transparent conductive film 60 ispart of a coating having the following structure: glass/silica 300Å/indium tin oxide 1350 Å/silicon nitride 125 Å/silicon oxynitride 600Å. In another example, the transparent conductive film 60 is part of acoating having the following structure: glass/indium tin oxide 1325Å/silicon nitride 440 Å.

In certain embodiments, the two opposed, external pane surfaces of theIG unit 110 are coated respectively with first 40 and second 60transparent conductive coatings. Reference is made to FIG. 6. In someembodiments of this nature, the first transparent conductive coating 40has a different thickness than the second transparent conductivecoating. In addition, the first transparent conductive coating 40 mayhave a different thickness than the second transparent conductivecoating 60. The first transparent conductive coating 40 can, forexample, be or include a first transparent conductive film comprisingboth indium and tin, while the second transparent conductive coating 60can be or include a second transparent conductive film comprising bothindium and tin. In such cases, the first transparent conductive film canhave a thickness of from 600 to 900 angstroms, while the secondtransparent conductive film has a thickness of from 900 to 1,500angstroms. A hydrophilic film (e.g., TiO₂) can optionally be providedover the first transparent conductive film. Thus, coating 40 can be atransparent conductive coating, a hydrophilic coating, or both. Whenprovided, the hydrophilic film can optionally have a thickness of from20 to 175 angstroms. As just a few examples, the first 40 and second 60transparent conductive coatings have the following structures:

-   first transparent conductive coating 40; glass/silica 35 Å/indium    tin oxide 1200 Å/silicon nitride 95 Å/silicon oxynitride 805 Å/TiO₂    60Å, and-   second transparent conductive coating 60; glass/silica 300 Å/indium    tin oxide 1350 Å/silicon nitride 125 Å/silicon oxynitride 600 Å, or-   first transparent conductive coating 40; glass/silica 35 Å/indium    tin oxide 1200 Å/silicon nitride 95 Å/silicon oxynitride 805 Å/TiO₂    60Å, and-   second transparent conductive coating 60; glass/indium tin oxide    1325 Å/silicon nitride 440 Å, or-   first transparent conductive coating 40; glass/SiO₂ 100 Å/indium tin    oxide 790 Å/Si₃N₄ 125 Å/silicon oxynitride 750 Å/TiO₂ 75Å, and-   second transparent conductive coating 60; glass/indium tin oxide    1325 Å/silicon nitride 440 Å, or-   first transparent conductive coating 40; glass/SiO₂ 100 Å/indium tin    oxide 790 Å/Si₃N₄ 125 Å/silicon oxynitride 750 Å/TiO₂ 75 Å, and-   second transparent conductive coating 60; glass/silica 300 Å/indium    tin oxide 1350 Å/silicon nitride 125 Å/silicon oxynitride 600 Å.

The substrate 10 with the controlled transmission coating 20 has anumber of beneficial properties. The ensuing discussion reports severalof these properties. In some cases, properties are reported for a single(i.e., monolithic) pane 10 bearing the present coating 20 on onesurface. In such cases, the reported properties are for a pane of clear3 mm soda lime float glass. In other cases, properties are reported foran IG unit 110 having the present coating 20 on its #2 surface. In suchcases, the reported properties are for a double-glazed IG unit whereinboth panes are clear 3 mm soda lime float glass with a ½ inchbetween-pane space filled with an insulative gas mix of 90% argon and10% air. These specifics are, of course, by no means limiting to theinvention. As just one example, the controlled transmission coating canalternatively be provided on the #3 surface of an IG unit. Absent anexpress statement to the contrary, the present discussion reportsdeterminations made using the well-known WINDOW 7.1 computer program(e.g., calculating center of glass data) under NFRC100-2010 conditions.

The controlled transmission coating 20 provides good thermal insulatingproperties. For example, the sheet resistance of the present coating 20is less than 5.0 Ω/square. Preferably, the sheet resistance of thiscoating 20 is less than 3.6 Ω/square. While the desired level of sheetresistance can be selected and varied to accommodate differentapplications, certain preferred coating embodiments (e.g., the exemplaryfilm stacks disclosed herein) provide a sheet resistance of less than3.0 Ω/square, such as from 1.0 to 2.9 Ω/square. The sheet resistance ofthe coating can be measured in standard fashion using a 4-point probe.

The coating 20 also has desirably low emissivity. For example, theemissivity of the coating 20 is less than 0.05. Preferably, theemissivity of this coating 20 is less than 0.04. While the desired levelof emissivity can be selected and varied to accommodate differentapplications, certain preferred coating embodiments (e.g., the exemplaryfilm stacks disclosed herein) provide an emissivity of less than 0.03,such as from 0.010 to 0.029. In one example, the emissivity is about0.028. In contrast, an uncoated pane of clear glass would typically havean emissivity of about 0.84.

The term “emissivity” is well known in the present art. This term isused herein in accordance with its well-known meaning to refer to theratio of radiation emitted by a surface to the radiation emitted by ablackbody at the same temperature. Emissivity is a characteristic ofboth absorption and reflectance. It is usually represented by theformula: E=1−Reflectance. The present emissivity values can bedetermined as specified in “Standard Test Method For Emittance OfSpecular Surfaces Using Spectrometric Measurements” NFRC 301-2010, theentire teachings of which are incorporated herein by reference.

In addition to low sheet resistance and low emissivity, the presentcoating 20 provides good solar heat gain properties. As is well known,the solar heat gain coefficient (SHGC) of a window is the fraction ofincident solar radiation that is admitted through a window. There are anumber of applications where low solar heat gain windows are ofparticular benefit. In warm climates, for example, it is desirable tohave low solar heat gain windows. For example, solar heat gaincoefficients of about 0.4 and below are generally recommended forbuildings in the southern United States. Further, windows that areexposed to a lot of undesirable sun benefit from having a low solar heatgain coefficient. Windows on the east or west side of a building, forinstance, tend to get a lot of sun in the morning and afternoon. Forapplications like these, the solar heat gain coefficient plays a role inmaintaining a comfortable environment within the building. Thus, it isbeneficial to provide windows of this nature with coatings thatestablish a low solar heat gain coefficient (i.e., low solar heat gaincoatings). Low solar heat gain coatings are, in fact, desirable for manywindow applications. However, some of these coatings have not offered asufficient balance of desirable properties to be adopted more broadly.

A tradeoff is sometimes made in low solar heat gain coatings whereby thefilms selected to achieve a low SHGC have the effect of decreasing thevisible transmittance to an even lower level than is desired and/orincreasing the visible reflectance to a higher level than is ideal. As aconsequence, windows bearing these coatings may have unacceptably lowvisible transmission, a somewhat mirror-like appearance, or both.

The present coating 20 provides a desirable low solar heat gaincoefficient. For example, the solar heat gain coefficient of the presentIG unit 110 is less than 0.4. Preferably, the present IG unit 110 has asolar heat gain coefficient of less than 0.25, such as from 0.10 to0.26. While the desired SHGC level can be selected and varied toaccommodate different applications, certain preferred embodiments (e.g.,using the exemplary film stacks disclosed herein) provide an IG unit 110having a solar heat gain coefficient of less than 0.23, such as from0.10 to 0.22. In some examples, the SHGC is about 0.176. Thus, the SHGCis less than 0.2 in certain embodiments. The present coating 20 canprovide a SHGC within any one or more of these ranges while at the sametime providing exceptional color (as specified by the color rangesreported below) and a visible transmission controlled to remain in oneor more of the transmission ranges reported below.

The term “solar heat gain coefficient” is used herein in accordance withits well-known meaning. Reference is made to NFRC 200-2014, the entireteachings of which are incorporated herein by reference. The SHGC can becalculated using the methodology embedded in the well-known WINDOW 7.1computer program.

Further, the U Value of the present IG unit is low. As is well known,the U Value of an IG unit is a measure of the thermal insulatingproperty of the unit. The smaller the U value, the better the insulatingproperty of the unit. The U Value of the present IG unit is less than0.4. Preferably, the present IG unit 110 has a U Value of less than0.35. While the desired U value can be selected and varied toaccommodate different applications, certain preferred embodiments (e.g.,using the exemplary film stacks disclosed herein) provide an IG unit 110having a U value of less than 0.3, such as from 0.10 to 0.29. In someexamples, the U value is about 0.244. Thus, the U value is less than0.25 in certain embodiments. The present coating 20 can provide a Uvalue within any one or more of these ranges while at the same timeproviding exceptional color (as specified by the color ranges reportedbelow) and a visible transmission controlled to remain in one or more ofthe transmission ranges reported below.

The term U Value is well known in the present art. It is used herein inaccordance with its well-known meaning to express the amount of heatthat passes through one unit of area in one unit of time for each unitof temperature difference between a hot side of the IG unit and a coldside of the IG unit. The U Value can be determined in accordance withthe standard specified for U_(winter) in NFRC 100-2014, the teachings ofwhich are incorporated herein by reference.

In combination with the beneficial thermal insulating propertiesdiscussed above, the present coating 20 has desirable opticalproperties. As noted above, a tradeoff is sometimes made in low solarheat gain coatings whereby the films selected to achieve good thermalinsulating properties have the effect of providing sub-optimal colorproperties. To the contrary, the present coating 20 provides a desirablecombination of thermal insulation and optical properties.

The present IG unit 110 has a visible transmittance T_(vis) in the rangeof from 0.3 to 0.5. While the desired level of visible transmittance canbe selected and varied to accommodate different applications, certainpreferred embodiments (e.g., the exemplary film stacks disclosed herein)provide an IG unit 110 having a visible transmittance in the range offrom 0.35 to 0.45, such as about 0.39 to 0.41.

The term “visible transmittance” is well known in the art and is usedherein in accordance with its well-known meaning to refer to thepercentage of all incident visible radiation that is transmitted throughthe IG unit 110. Visible radiation constitutes the wavelength range ofbetween about 380 nm and about 780 nm. Visible transmittance, as well asvisible reflectance, can be determined in accordance with NFRC 300-2014,Standard Test Method for Determining the Solar and Infrared OpticalProperties of Glazing Materials and Fading Resistance of Systems(National Fenestration Rating Council Incorporated, adopted December2001, published January 2002). The well-known WINDOW 7.1 computerprogram can be used in calculating these and other reported opticalproperties.

As noted above, a limitation of some high shading ability coatings isthey reflect more visible light than is optimal. While it is known toanti-reflect the infrared-reflective films in these coatings (e.g., bysandwiching each infrared-reflective film between transparent dielectricfilms), a tradeoff is sometimes made in high shading ability coatings,whereby the films selected to achieve a low SHGC have the effect ofrestricting the visible reflectance to a level that is less than ideal.As a consequence, windows bearing these coatings may have a somewhatmirror-like appearance.

To the contrary, the present coating 20 has sufficiently low visiblereflectance to obviate this mirror-like appearance problem. For example,the present IG unit 110 has an exterior visible reflectance R_(exterior)of less than 20%. Preferably, the visible reflectance R_(exterior) ofthe IG unit 110 is less than 15%. While the precise level of the IGunit's exterior visible reflectance can be selected and varied inaccordance with the present teachings, certain preferred embodiments(e.g., where the coating 20 is one of the film stacks detailed below)achieve an exterior visible reflectance R_(exterior) of less than 14%,such as from 5% to 13%. In some examples, the exterior visiblereflectance R_(exterior) is about 11%. Thus, the exterior visiblereflectance R_(exterior) is 12% or less in certain embodiments. exterioris 12% or

The term “visible reflectance” is well known in the present art and isused herein in accordance with its well-known meaning to refer to thepercentage of all incident visible radiation that is reflected off theexterior side 110E of the IG unit 110. The reported visible reflectanceis measured off a central portion of the exterior side 110E of the IGunit 110 and is indicated as R_(exterior).

The present coating 20 provides desirable color properties, particularlygiven the balance of other properties it achieves. The coating 20 iswell suited for applications in which reflected color is of concern. Thefollowing discussion of color is reported using the well-known colorcoordinates of “a” and “b.” In particular, these color coordinates areindicated herein using the subscript h (i.e., a_(h) and b_(h)) torepresent the conventional use of the well-known Hunter Lab Color System(Hunter methods/units, Ill. D65, 10 degree observer). The present colorproperties can be determined as specified in ASTM Method E 308, theentire teachings of which are incorporated herein by reference.

The present IG unit 110 has a desirably neutral appearance inreflection, with any appreciable color being of a pleasing hue. Thereflected color reported herein is as viewed from the exterior side 110Eof the present IG unit. In some embodiments, the present IG unit 110exhibits a reflected color characterized by an a_(h) color coordinate ofbetween −9 and 6, and a b_(h) color coordinate of between −15 and −3. Inone example, the a_(h) color coordinate is between −7 and 1 (such asabout −3.1), and a b_(h) color coordinate of between −13 and −5 (such asabout −9.2). These embodiments represent a broader embodiment groupwherein (whether or not a_(h) and b_(h) are within the ranges notedabove) the present IG unit 110 has an exterior reflected colorcharacterized by a chroma magnitude number (defined as the square rootof [a_(h) ²+b_(h) ²]) of less than 17, preferably less than 14, andperhaps optimally less than 12.

The magnitude of at least one of the a_(h) and b_(h) coordinatespreferably is negative (in some embodiments, both are negative). Incertain embodiments, at least one these color coordinates (e.g., b_(h))is significantly away (i.e., by at least 5 or at least 7 in magnitude)from the vertical and/or horizontal axes of the color space (i.e., awayfrom the “zero” coordinates). As one approaches the vertical and/orhorizontal axes of the color space, a small change in the magnitude ofa_(h) or b_(h) may translate into a considerable change in terms ofactual appearance, the less desirable yellow or red zones being therebyencroached.

The present IG unit 110 can also provide a pleasing transmitted color.Preferably, the IG unit 110 exhibits a transmitted color characterizedby an a_(h) color coordinate of between −15 and −1, and a b_(h) colorcoordinate of between −10 and 4. In certain preferred embodiments (e.g.,the preferred film stack disclosed herein), the IG unit 110 exhibits atransmitted color characterized by an a_(h) color coordinate of between−12 and 4 (such as about −8.4), and a b_(h) color coordinate of between−7 and 1 (such as about −3.3). These embodiments represent a broaderembodiment group wherein (whether or not the a_(h) and b_(h) are withinthe ranges noted above) the magnitude of at least one (optionally each)of the a_(h) and b_(h) coordinates is negative (and optionally has amagnitude of at least 2) for transmitted color.

A first exemplary film stack in accordance with the invention will nowbe described. The layers of this coating will be described in order,moving outwardly (i.e., in a direction away from the substrate).Directly upon the substrate, there is formed a layer comprising silicondioxide. This layer preferably has a thickness of between 80 angstromsand 350 angstroms, such as about 230 angstroms. Directly upon this layerthere is formed a layer of zinc tin oxide. The thickness of this zinctin oxide layer is preferably between 70 angstroms and 350 angstroms,such as about 195 angstroms. An infrared-reflective silver layer isformed directly upon this zinc tin oxide layer. This silver layerpreferably has a thickness of between 75 angstroms and 150 angstroms,such as about 115 angstroms. A metallic nickel-aluminum film is thenapplied directly upon this silver layer. In the present example, thenickel-aluminum layer is deposited as metallic nickel-aluminum film.Some of the nickel-aluminum is oxidized during the deposition of anoverlying oxide layer, as described above. This nickel-aluminum blockerfilm is preferably deposited at a thickness of between 10 angstroms and90 angstroms, such as about 25 angstroms. Directly upon thisnickel-aluminum layer is applied a layer of zinc tin oxide, whichpreferably has a thickness of between 400 angstroms and 1,200 angstroms,such as about 835 angstroms. An infrared-reflective silver layer isformed directly upon this zinc tin oxide layer. This silver layerpreferably has a thickness of between 80 angstroms and 220 angstroms,such as about 165 angstroms. A metallic nickel-aluminum blocker film isthen applied directly upon this silver layer. This nickel-aluminum filmpreferably is deposited at a thickness of between 30 angstroms and 80angstroms, perhaps optimally about 50 angstroms. Directly upon thisnickel-aluminum film is applied a layer of zinc tin oxide, whichpreferably has a thickness of between 400 angstroms and 1,200 angstroms,such as about 680 angstroms. Directly upon this zinc tin oxide layer isdeposited an infrared-reflective silver layer. This silver layerpreferably has a thickness of between 80 angstroms and 220 angstroms,such as about 170 angstroms. A metallic nickel-aluminum blocker film isthen applied directly upon this silver layer. This nickel-aluminum filmpreferably is deposited at a thickness of between 30 angstroms and 80angstroms, such as about 50 angstroms. Directly upon thisnickel-aluminum film is applied a layer of zinc tin oxide, whichpreferably has a thickness of between 50 angstroms and 350 angstroms,such as about 270 angstroms. Directly upon this zinc tin oxide layer isdeposited a layer comprising silicon nitride, which preferably forms theoutermost layer of the film stack. Preferably, this silicon nitridelayer has a thickness of between 100 angstroms and 300 angstroms, suchas about 260 angstroms.

A second exemplary film stack in accordance with the invention will nowbe described. The layers of this coating will be described in order,moving outwardly (i.e., in a direction away from the substrate).Directly upon the substrate, there is formed a layer comprising silicondioxide. This layer preferably has a thickness of between 80 angstromsand 350 angstroms, such as about 230 angstroms. Directly upon this layerthere is formed a layer of zinc tin oxide. The thickness of this zinctin oxide layer is preferably between 70 angstroms and 350 angstroms,such as about 260 angstroms. An infrared-reflective silver layer isformed directly upon this zinc tin oxide layer. This silver layerpreferably has a thickness of between 75 angstroms and 150 angstroms,such as about 135 angstroms. A metallic nickel-aluminum film is thenapplied directly upon this silver layer. In the present example, thenickel-aluminum layer is deposited as metallic nickel-aluminum film.Some of the nickel-aluminum is oxidized during the deposition of anoverlying oxide layer, as described above. This nickel-aluminum blockerfilm is preferably deposited at a thickness of between 10 angstroms and90 angstroms, such as about 13 angstroms. Directly upon thisnickel-aluminum layer is applied a layer of zinc tin oxide, whichpreferably has a thickness of between 400 angstroms and 1,200 angstroms,such as about 845 angstroms. An infrared-reflective silver layer isformed directly upon this zinc tin oxide layer. This silver layerpreferably has a thickness of between 80 angstroms and 220 angstroms,such as about 165 angstroms. A metallic nickel-aluminum blocker film isthen applied directly upon this silver layer. This nickel-aluminum filmpreferably is deposited at a thickness of between 30 angstroms and 80angstroms, perhaps optimally about 35 angstroms. Directly upon thisnickel-aluminum film is applied a layer of zinc tin oxide, whichpreferably has a thickness of between 400 angstroms and 1,200 angstroms,such as about 675 angstroms. Directly upon this zinc tin oxide layer isdeposited an infrared-reflective silver layer. This silver layerpreferably has a thickness of between 80 angstroms and 220 angstroms,such as about 175 angstroms. A metallic nickel-aluminum blocker film isthen applied directly upon this silver layer. This nickel-aluminum filmpreferably is deposited at a thickness of between 30 angstroms and 80angstroms, such as about 40 angstroms. Directly upon thisnickel-aluminum film is applied a layer of zinc tin oxide, whichpreferably has a thickness of between 50 angstroms and 350 angstroms,such as about 225 angstroms. Directly upon this zinc tin oxide layer isdeposited a layer comprising silicon nitride, which preferably forms theoutermost layer of the film stack. Preferably, this silicon nitridelayer has a thickness of between 100 angstroms and 300 angstroms, suchas about 210 angstroms.

Given the present teaching as a guide, those skilled in the present artwould be able to readily select many other suitable layer compositionsand thicknesses that produce good results.

The controlled transmission coating 20 is particularly advantageous foruse in laminated glass assemblies. The low visible transmission and goodselectivity of the coating 20 provide such laminated glass assemblieswith good filtering of solar radiation, and the exceptional chemicaldurability offers particular advantage in terms of withstandingcorrosion from the cut edges of the laminated glass. FIG. 7 shows onesuch embodiment wherein two glass panes 10, 10′ are laminated togetherwith a polymer interlayer 70 sandwiched between the two panes.

Here, the controlled transmission coating 20 is on the second surface 14of the first pane 10.

One aspect of the invention provides methods of depositing anickel-aluminum blocker film. The nickel-aluminum film can be depositedby sputter deposition (i.e., sputtering). Sputtering techniques andequipment are well known in the present art. For example, magnetronsputtering chambers and related equipment are available commerciallyfrom a variety of sources (e.g., Von Ardenne GmbH, of Dresden, Germany,or Von Ardenne North America, Inc., of Perrysburg, Ohio, USA). Usefulmagnetron sputtering techniques and equipment are also disclosed in U.S.Pat. No. 4,166,018, issued to Chapin, the teachings of which areincorporated herein by reference.

Thus, conventional magnetron sputtering techniques and equipment can beused to deposit the nickel-aluminum film. Techniques and equipment ofthis nature are best understood with reference to FIG. 8, wherein thereis illustrated a sputtering chamber 200 equipped with two cathodes. Eachcathode includes a sputtering target 220 a, 220 b, end blocks 240, and amagnet array (not shown) and cooling lines (not shown) within thetarget. While the illustrated chamber 200 is provided with two cathodes,it may be desirable to employ a single cathode instead. Also shown inFIG. 8 are anodes 230, gas distribution pipes 235, and transport rollers210 for conveying the substrate 10 through the chamber 200. Sputteringequipment of this nature is well known in the present art.

The sputtering targets 220 a, 220 b illustrated in FIG. 8 are depictedas being cylindrical magnetron targets (i.e., C-Mags). However, any typeof sputtering target (e.g., planar or cylindrical) can be used. Forexample, the sputtering chamber can alternatively be provided with asingle planar target. The selection of appropriate planar and/orcylindrical targets is well within the purview of skilled artisans.

In one method of the invention, a nickel-aluminum film is deposited bysputtering one or more targets having a sputterable target materialcomprising an alloy or mixture of nickel and aluminum. For example, thetarget material may comprise about 90% metallic nickel and about 10%metallic aluminum. The percentages of nickel and aluminum in the targetmaterial can be varied as desired. While the target material may consist(or consist essentially) of nickel and aluminum, it is anticipated thatthe target material may include one or more other materials in additionto nickel and aluminum (such as titanium and/or oxygen). Nickel-aluminumtargets can be manufactured by Soleras Advanced Coatings BVBA, ofDeinze, Belgium.

In another method of the invention, nickel-aluminum film is deposited byco-sputtering. Co-sputtering is a process in which two or more targetsof different composition are sputtered simultaneously. Thenickel-aluminum layer can be deposited by co-sputtering anickel-containing target and an aluminum-containing target in the samesputtering chamber or zone. Thus, one of the targets 220 a, 220 b in theillustrated chamber 200 may be a nickel-containing target and the othermay be an aluminum-containing target. For example, the targets 220 a,220 b may be formed respectively of nickel compound (e.g., alloy) andmetallic aluminum. Alternatively, the targets 220 a, 220 b may be formedrespectively of a nickel compound and an aluminum compound. Nickelcompound targets, as well as aluminum targets and aluminum compoundtargets, are available from a number of commercial suppliers, such asW.C. Heraeus of Hanau, Germany. The term “nickel-containing” is usedherein to refer to any material that contains at least some nickel. Theterm “aluminum-containing” is used herein to refer respectively to anymaterial that contains at least some aluminum.

Thus, the present co-sputtering method comprises providing anickel-containing target and an aluminum-containing target. Both targetsare positioned in a sputtering chamber having a sputtering cavity inwhich a controlled environment can be established. One or more powersupplies are provided for delivering electric charge (e.g., cathodiccharge) to both targets. The cathodes are then energized to sputternickel and aluminum onto a substrate, thereby depositing thenickel-aluminum layer upon a film layer previously deposited upon thesubstrate (e.g., onto a previously deposited infrared-reflective layer,beneath which there may be other previously deposited films, asdescribed above). The nickel-containing target and thealuminum-containing target may be sputtered at substantially the sametime (e.g., simultaneously) or in succession. A first power level isselected for delivery of electric charge to the nickel-containing targetand a second power level is selected for delivery of electric charge tothe aluminum-containing target. These power levels are selected todeposit desired percentages of nickel and aluminum. In certain preferredembodiments, the first power level is greater than the second powerlevel.

As can now be appreciated, preferred methods of the invention involvedepositing the protective nickel-aluminum layer by sputtering, whetherconventionally or by co-sputtering. With continued reference to FIG. 8,there is provided a substrate 10 carrying a partial coating 114 thatincludes at least one infrared-reflective film. The infrared-reflectivefilm will typically be positioned over a transparent dielectric film,and in most cases will define the outermost face of the partial coating114 (prior to deposition thereon of the nickel-aluminum film). As willbe apparent to those skilled in the art, one or more other films may beformed between the substrate and the transparent dielectric film and/orbetween the transparent dielectric film and the infrared-reflectivefilm. For example, the partial coating 114 may take the form of the filmstack portion beneath, and including, any one of the infrared-reflectivefilms 50, 150, 130 depicted in FIGS. 1-2. In one particular method, thepartial coating 114 includes an exposed, outermost infrared-reflectivesilver or silver-containing film that is carried directly over atransparent dielectric film (e.g., zinc tin oxide or zinc aluminumoxide).

The partially coated substrate 10 is positioned beneath one or moretargets 220 a, 220 b, which comprise both nickel and aluminum (eithercollectively or individually, depending on whether conventionalsputtering or co-sputtering is used). As depicted in FIG. 8, thesubstrate 10 can be positioned upon a plurality of transport rollers210. The target or targets are sputtered (i.e., energized) to deposit anickel-aluminum film upon the partially-coated substrate (in many cases,directly upon the exposed infrared-reflective film). During sputtering,the substrate 10 can be conveyed through the chamber 200 (e.g.,continuously and at constant speed). It is well known to drive (i.e.,rotate) one or more of the rollers 210 to convey the substrate 10through the chamber 200 (e.g., in the direction of the arrow shown inFIG. 8).

In some cases, it will be preferred to sputter the nickel-aluminumtarget or targets in a non-reactive (i.e., inert) atmosphere to depositthe nickel-aluminum film. This would be expected to yield anickel-aluminum film that is as reactive as possible, thus enabling itto capture a great deal of oxygen and/or nitrogen during deposition ofsubsequent films and/or during heat treatment. In this regard, asputtering atmosphere consisting essentially of noble gas (e.g., about100% argon) may be preferred. For example, argon at a pressure of about7×10⁻³ mbar (or about 5 mtorr) should give good results. As will beappreciated by skilled artisans, the power used is selected based on therequired thickness, the width of the coater, the coating speed, and thenumber of cathodes involved. Power levels of up to about 25 kW pertarget have been found to give good results in sputter depositing thenickel-aluminum film. Care should be taken to prevent accidental leakage(flow of reactive gases) into the area where the nickel-aluminum layeris sputtered under control. Any leak near the targets (at low powerlevels) could create local areas of oxidation in the nickel-aluminumlayer. This could create uniformity problems before and after tempering.The substrate 10 upon which the nickel-aluminum film is deposited can beconveyed through the sputtering chamber 200 at essentially any desiredspeed. For example, substrate speeds of between about 100-500 inches perminute should be suitable.

While sputtering techniques are presently contemplated to be preferredfor depositing the protective nickel-aluminum layer and the rest of thecoating 20, any suitable thin film deposition technique(s) can be used.For example, it may be possible to deposit one or more layers of thecoating (such as a film comprising silicon dioxide, and/or a filmcomprising silicon nitride) by plasma chemical vapor deposition (i.e.,CVD). Reference is made to U.S. Pat. No. 4,619,729 (Johncock et al.),U.S. Pat. No. 4,737,379 (Hudgens et al.), and U.S. Pat. No. 5,288,527(Jousse et al.), the teachings of which are incorporated herein byreference. Plasma CVD involves decomposition of gaseous sources via aplasma and subsequent film formation onto solid surfaces, such as glasssubstrates. The thickness of the resulting film can be adjusted byvarying the speed of the substrate as it passes through a plasma zoneand by varying the power and gas flow rate within each zone. Thoseskilled in the art would be able to select other suitable depositionmethods for applying the present nickel-aluminum layer.

While some preferred embodiments of the invention have been described,it should be understood that various changes, adaptations andmodifications may be made therein without departing from the spirit ofthe invention and the scope of the appended claims.

What is claimed is:
 1. A multiple-pane insulating glazing unit having abetween-pane space, the multiple-pane insulating glazing unit includinga pane having a surface coated with a low-emissivity coating, saidsurface of said pane being exposed to said between-pane space, thelow-emissivity coating comprising, in sequence moving outwardly fromsaid surface of said pane, a dielectric base coat comprising oxide film,nitride film, or oxynitride film, a first infrared-reflective layer, afirst nickel-aluminum blocker layer in contact with the firstinfrared-reflective layer, a first dielectric spacer coat comprising anoxide film in contact with the first nickel-aluminum blocker layer, asecond infrared-reflective layer, a second nickel-aluminum blocker layerin contact with the second infrared-reflective layer, a seconddielectric spacer coat comprising an oxide film in contact with thesecond nickel-aluminum blocker layer, a third infrared-reflective layer,a third nickel-aluminum blocker layer in contact with the thirdinfrared-reflective layer, and a dielectric top coat comprising an oxidefilm in contact with the third nickel-aluminum blocker layer, the first,second, and third infrared-reflective layers having a combined thicknessof between 375 angstroms and 650 angstroms in combination with thesecond and third nickel-aluminum blocker layers each being between 75%and 400% thicker than the first nickel-aluminum blocker layer, themultiple-pane insulating glazing unit having a visible transmittance ofbetween 0.3 and 0.5.
 2. The multiple-pane insulating glazing unit ofclaim 1 wherein the thickness of the first nickel-aluminum blocker layeris between 10 angstroms and 40 angstroms, the thickness of the secondnickel-aluminum blocker layer is between 20 angstroms and 60 angstroms,and the thickness of the third nickel-aluminum blocker layer is between20 angstroms and 60 angstroms.
 3. The multiple-pane insulating glazingunit of claim 2 wherein the first infrared-reflective layer has athickness of between 90 and 170 angstroms, the secondinfrared-reflective layer has a thickness of between 130 and 200angstroms, and the third infrared-reflective layer has a thickness ofbetween 130 and 200 angstroms, the first nickel-aluminum blocker layerhas a thickness of between 10 and 40 angstroms, the secondnickel-aluminum blocker layer has a thickness of between 25 and 75angstroms, and the third nickel-aluminum blocker layer has a thicknessof between 25 and 75 angstroms, the visible transmittance of themultiple-pane insulating glazing unit being between 0.35 and 0.45. 4.The multiple-pane insulating glazing unit of claim 3 wherein thedielectric base coat has a total optical thickness of between 500angstroms and 900 angstroms, the first dielectric spacer coat has atotal optical thickness of between 1,250 angstroms and 2,100 angstroms,the second dielectric spacer coat has a total optical thickness ofbetween 1,000 angstroms and 1,950.
 5. The multiple-pane insulatingglazing unit of claim 1 having the following properties in combination:solar heat gain coefficient of less than 0.18, U value of less than0.25, visible transmittance of between 0.35 and 0.45, and exteriorvisible reflectance of less than 0.14.
 6. The multiple-pane insulatingglazing unit of claim 1 wherein the first, second, and thirdinfrared-reflective layers each comprise metallic silver film, andwherein (i) the first nickel-aluminum blocker layer has an outerinterface and an inner interface, the outer interface of the firstnickel-aluminum blocker layer adheres to said oxide film of the firstdielectric spacer coat while the inner interface of the firstnickel-aluminum blocker layer adheres to the metallic silver film of thefirst infrared-reflective layer, the outer interface of the firstnickel-aluminum blocker layer comprising aluminum oxide, the innerinterface of the first nickel-aluminum blocker layer comprising metallicnickel, (ii) the second nickel-aluminum blocker layer has an outerinterface and an inner interface, the outer interface of the secondnickel-aluminum blocker layer adheres to said oxide film of the seconddielectric spacer coat while the inner interface of the secondnickel-aluminum blocker layer adheres to the metallic silver film of thesecond infrared-reflective layer, the outer interface of the secondnickel-aluminum blocker layer comprising aluminum oxide, the innerinterface of the second nickel-aluminum blocker layer comprisingmetallic nickel, and (iii) the third nickel-aluminum blocker layer hasan outer interface and an inner interface, the outer interface of thethird nickel-aluminum blocker layer adheres to said oxide film of thedielectric top coat while the inner interface of the thirdnickel-aluminum blocker layer adheres to the metallic silver film of thethird infrared-reflective layer, the outer interface of the thirdnickel-aluminum blocker layer comprising aluminum oxide, the innerinterface of the third nickel-aluminum blocker layer comprising metallicnickel.
 7. A laminated glass assembly comprising first and second glasspanes, a polymer interlayer, and a controlled transmission coating, thepolymer interlayer being sandwiched between the first and second glasspanes, the controlled transmission coating being on an internal surfaceof the first pane such that the controlled transmission coating islocated between the first pane and the polymer interlayer, thecontrolled transmission coating comprising, in sequence moving away fromthe internal surface of the first pane, a dielectric base coatcomprising oxide film, nitride film, or oxynitride film, a firstinfrared-reflective layer, a first nickel-aluminum blocker layer incontact with the first infrared-reflective layer, a first dielectricspacer coat comprising an oxide film in contact with the firstnickel-aluminum blocker layer, a second infrared-reflective layer, asecond nickel-aluminum blocker layer in contact with the secondinfrared-reflective layer, a second dielectric spacer coat comprising anoxide film in contact with the second nickel-aluminum blocker layer, athird infrared-reflective layer, a third nickel-aluminum blocker layerin contact with the third infrared-reflective layer, and a dielectrictop coat comprising an oxide film in contact with the thirdnickel-aluminum blocker layer, the first, second, and thirdinfrared-reflective layers each comprising silver.